3GPP Long Term Evolution (LTE) and Long Term Evolution Advanced (LTE-A) systems may operates in a Frequency Division Duplex (FDD) mode or a Time Division Duplex (TDD) mode. In the FDD mode, two different frequencies are used for uplink and downlink transmission, and the base station and user equipment may send and receive data at the same time. In the TDD mode, the same frequency is used for uplink and downlink transmission, and the base station and user equipment cannot send and receive data at the same time. Therefore, in the TDD mode, the LTE system has configurations specifying subframes for either uplink or downlink.